为什么亚军用runner-up表示?

runner-up
n. 亚军, 亚军队
[经] (拍卖时)高喊货价的人牛津高阶英语词典

runner-up
noun
(plural runners-up) a person or team that finishes second in a race or competition; a person or team that has not finished first but that wins a prize: Winner:
Kay Hall. Runner-up:
Chris Platts. ◆ They finished runners-up behind Sweden. ◆ The runners-up will all receive a £40 prize

有个意思是指赢家而非首名者, 特别是第二名, 意思就是runner-up 泛指非冠军的赢家。

这个, 我跑去查查网上字典, 看了 Oxford Advanced Learner's Dictionary :
runner-up noun (pl. runners-up) a person or team that finishes second in a race or competition; a person or team that has not finished first but that wins a prize: Winner: Kay Hall. Runner-up: Chris Platts. They finished runners-up behind Sweden. The runners-up will all receive a £50 prize.
和 Merriam-Webster Online Dictionary:
the competitor that does not win first place in a contest; especially : one that finishes in second place

它们的意思